private CGPoint?GetSnapScrollPosition(UIScrollView scrollView, nfloat velocity, CGPoint offset)
{
CarouselCollectionView collectionView = null;
if (!_collectionView.TryGetTarget(out collectionView))
{
return(null);
}
var count = _carousel?.Items?.Count;
if (!(count >= 0))
{
return(null);
}
var location = velocity >= 0 ? offset : new CGPoint(offset.X + collectionView.Frame.Width, 0);
var currentIndex = collectionView.IndexPathForItemAtPoint(location);
if (currentIndex == null)
{
return(null);
}
var currentRect = collectionView.GetLayoutAttributesForItem(currentIndex);
NSIndexPath newIndex = currentIndex;
if ((Math.Abs(velocity) > _velocityThreshold && velocity > 0 ||
offset.X > currentRect.Frame.Left + currentRect.Bounds.Size.Width / 2) &&
currentIndex.Row < count - 1)
{
newIndex = NSIndexPath.FromRowSection(currentIndex.Row + 1, 0);
}
else if ((Math.Abs(velocity) > _velocityThreshold && velocity < 0 ||
offset.X < currentRect.Frame.Left - currentRect.Bounds.Size.Width / 2) &&
currentIndex.Row > 0)
{
newIndex = NSIndexPath.FromRowSection(currentIndex.Row - 1, 0);
}
UICollectionViewLayoutAttributes newRect = currentRect;
if (newIndex != currentIndex)
{
CurrentIndex = newIndex.Row;
newRect = collectionView.GetLayoutAttributesForItem(newIndex);
var item = _carousel.Items[CurrentIndex];
_carousel.Current = item;
}
return(newRect.Frame.Location);
}
public void SnapToCurrentIndex(bool animated = true)
{
if (!(CurrentIndex >= 0 && _carousel?.Items?.Count > 0))
{
return;
}
CarouselCollectionView collectionView = null;
if (!_collectionView.TryGetTarget(out collectionView))
{
return;
}
var index = NSIndexPath.FromRowSection(CurrentIndex, 0);
var rect = collectionView.GetLayoutAttributesForItem(index);
var duration = animated ? 0.2f : 0f;
UIView.Animate(duration, () => {
collectionView.ContentOffset = rect.Frame.Location;
});
}
public CarouselSource(Carousel carousel, CarouselCollectionView collectionView)
{
_collectionView = new WeakReference <CarouselCollectionView>((CarouselCollectionView)collectionView);
_carousel = carousel;
}
